In a field like medical laboratory or biology laboratory, a liquid sample such as feces, urine or river water needs to be filtered by a filtering container. The filtering container in the prior arts, for example, a disposable feces concentration container is illustrated in FIGS. 1 and 2. In FIG. 1, a safety catch 101 at the top of the container is removed manually and then a hole at the bottom of the container is pierced by a finger to allow the liquid flowing downwardly to pass through the filter screen at the bottom. Alternatively, in FIG. 2, the safety plug 202 at a side of the container is pulled manually to open the center hole and allow the liquid flowing downwardly. The prior arts have the defects that the container is just opened by the manual control of the top safety catch or the side safety plug and cannot be shut, and the filtering amount cannot be controlled so that all the liquid in the container must be filtered at a time.